Add buildx history command

These commands allow working with build records
of completed and running builds.

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

vendor/github.com/pkg/browser/README.md

@@ -0,0 +1,55 @@
+
+# browser
+    import "github.com/pkg/browser"
+
+Package browser provides helpers to open files, readers, and urls in a browser window.
+
+The choice of which browser is started is entirely client dependant.
+
+
+
+
+
+## Variables
+``` go
+var Stderr io.Writer = os.Stderr
+```
+Stderr is the io.Writer to which executed commands write standard error.
+
+``` go
+var Stdout io.Writer = os.Stdout
+```
+Stdout is the io.Writer to which executed commands write standard output.
+
+
+## func OpenFile
+``` go
+func OpenFile(path string) error
+```
+OpenFile opens new browser window for the file path.
+
+
+## func OpenReader
+``` go
+func OpenReader(r io.Reader) error
+```
+OpenReader consumes the contents of r and presents the
+results in a new browser window.
+
+
+## func OpenURL
+``` go
+func OpenURL(url string) error
+```
+OpenURL opens a new browser window pointing to url.
+
+
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+- - -
+Generated by [godoc2md](http://godoc.org/github.com/davecheney/godoc2md)